Double-acting drill bit



Jan. 27 1953 J. E. QRTLol-'F DOUBLE-ACTING DRILL BIT Filed June 6, 1951 .1 w I' IV I' l.' v T. /A//////t//// ff v@ ,AAA ZV /w /J 2 w w 9 7 .91 4 uwfw i ,L i @s ml; -.-2.-- Il N &\\\\\\ w m/////./ lv/ A .4 2 2 2 Patented Jan. 27, 1953 DOUBLE-ACTING Darm. err

John E. Ortloff, Tulsa, Okla., assignor to Standard Oil Development Company, a corporation ot Delaware Application June 6, 1951, Serial No. 230,177

The present invention concerns an improved type of drill bit for drilling bore holes in the earth. More particularly it relatesto a double acting drill bit wherein the central portion ofthe bit is drivenat a higher speed than the outer portion. In present day practice the drilling of a large proportion of the bore holes in the earth for the production of crude petroleum oil from underlying oil bearing strata is accomplished by what is known as rotary drilling. In this method drill pipe is run into the full length of the bore hole 4 Claims. (Cl. Z55-4) and is provided with abit at its lower end. The

time if such formations are encountered. It has also been found that diamond coring bits will drill through such formations much more emciently than the usual rock bits. However, the use of diamond core bits for drilling has the disadvantage that the drill pipe must be pulled out of the hole at regular intervals in order to remove the core. Although cores of up to 90 feet in length can be taken at onetime a great reduction in cost could be effected if the cored section could be drilled or ground up as the drilling progresses inasmuch as a diamond core bit can cut in excess of 500 feet of core before requiring replacement. Hence it has been proposed to employ full hole diamond bits rather than coring bits. These have usually not been entirely satisfactory because of the inherent fact that the linear velocity of the outer periphery of the bit is much greater than at the center of the bit. As a result the outer edge or rim of the bit cuts its way through before the center does and imposes all of the bit load on the center diamonds, which causes them to fail prematurely. One solution 4that has been employed to overcome this difcultyhas been to make a. bit that cuts a core, which is then ground up by secondary cutters or grinders. An alternative solution to the problem has been to provide a bit having a plurality of co-planar cutters, one of the cutters being of sumcient diameter to overlie the geometrical center of the hole being drilled. Such drill bits have left much to be desired however in view ot the necessity for independent drives such as systems of planetary gearing for rotating the secondary cutters or grinders in the nrst solution mentioned or the plurality of Acutters in the second solution mentioned, as well as gripping means to engage the wall of the bore hole to provide the necessary torque for the secondary drive.

Itis one object of the present invention to provide an abrasive type bit that will drill a full hole more etllciently than can be done with conventional full hole diamond bits. y

It is another object of the invention to provide a full hole abrasive drill bit having a minimum of moving parts while nevertheless ensuring at least as great a cutting speed at the center of the hole as at the edges of the hole.

In accordan-ce with this invention a drill bit assembly is provided which comprises a tubular case that is attachedA to the lower end of a drill pipe, the case carrying on its lower end a coring head such as a, conventional diamond core head. or similar coring means employing abrasive particles, behind which is rotatably mounted secondary cutting means on a central shaft which is driven by a multi-stage hydraulic turbine built into the assembly. Ihe rotor plates of the turbine are on thecentral shaft driving the secondary cutting means and the stator blades are in the outer case which drives the coring head.

The nature of the invention will be more readily understood from the ensuing description when read in conjunction with the accompanying drawing in which Fig. 1 is an elevational view, partly in section, of the upper portion of one embodiment of the invention and Fig. 2 is a lower continuation of Fig. 1.

Referring now to the drawing-it will be seen that an outer tubular case or shell I2 is provided which is made in two separable sections I2 and I3. The upper section I2 is readily screwed onto the lower portion of drill pipe I I. A more or less conventional diamond core head I4 is screwed onto the bottom of the lower section I3. Concentrically disposed within the lower tubular section I3 is a tubular shaft I5 which deilnes with case I3 an annular chamber into which are fitted combination thrust and radial bearings I6 and I1,

which rotatably support shaft I5. Attached to rock bit. Bearings I6 and I'I are protected from contamination from drilling mud by cup type packingseals I9 which are held in place by bronze follower rings 20. Disposed within' the central portion of the upper half I2 of the outer case is a central shaft 2| provided with a plurality of rotor blades 23. Shaft 2 I is rotatably supported by thrust bearings 22 which are protected from mud contamination by seal 25 held in place by follower ring 26. Cooperatively placed with respect to rotor blades 23 and attached to the interior of upper case section I2 are a plurality of stator blades 24 so that the assembly constitutes a multi-stage turbine which will rotate shaft I5 when drilling mud is conducted downward through the drill pipe, through mud passages 28, past the turbine blades, through chamber 29, mud ports 30, central passageway II and mud ports 32. Preferably central bit Il is placed above coring head I4 a suiilcient distance to provide a passageway 33 so that some of the mud may pass out through mud ports I4' and back up the borehole. The direction of mud flow is indicated by the arrows. v

The hydraulic turbine comprising shaft 2| and the rotor and stator blades 23 and 24 is preferably so designed that the central shaft will be turned in the same direction as the outer case and drill pipe; thus the central bit I8 will/tum at least as fast or faster than the coring ad I4, making it possible to grind up the core made by coring head I4 as fast as the core is fed into the bit.

One of the important features of this invention is that rotation of the inner bit is achieved without the use of wall gripping devices to resist the reactive torque producedwhen the inner bit is rotated, this torque being resisted by the drill stem. Also, no planetary gearing is used to increase the speed of the central shaft. Another important feature of the invention is that mud and cuttings are effectively sealed off from the bearings and other vital parts of the bit and mud flow through the bit as well as return flow is not restricted.

It is not intended that this invention be interpreted as limited to the specific embodiments described, as modications thereof are possible without departing from the spirit of the invention whose scope is limited only by the following claims.

What is claimed is:

1. A drill bit assembly comprising an elongated tubular case attachable to the lower end of a drill pipe, a coring head held by the lower end of said case, said coring head having a central opening for receiving a core, a plurality of abrasive particles held by said coring head. a tubular shaft disposed within said case lengthwise thereof and dening with the interior wall of said case an annular chamber, bearings in said annular chamber rotatably supporting said tubular shaft, sealing means in said annular chamber isolating said bearings from fluid in said chamber, secondary cutting means fixed to the bottom of said tubular shaft above said coring head adapted to grind up \a core entering said central opening, turbine drive means in said case attached to said shaft and adapted to rotate the same and provided with at least one entering port communicating with said drill pipe and with at least one exit port terminating within said tubular shaft.

2. Drill bit assembly according lto claim 1 wherein said secondary cutting means comprises an essentially circular bit carrying abrasive particles.

3. Drill bit assembly .according to claim 1 wherein at least one fluid port is provided in the wall of said case, terminating in said annular chamber below saidl sealing means.

4. Drill bit assembly according to claim 1 wherein said turbine drive means comprises a plurality of vertically spaced rotor blades placed in said annular chamber and fixed to said tubular shaft and a plurality of stator blades cooperatively placed in said annular 'chamber with respect to said rotor blades and attached to the inner wall of said case.

JOHN E. oRTLbFF.

ille of this patent:

UNITED STATES PATENTS Name Date Stone Feb. 14, 1950 Number 

